1. Field of the Invention
This invention relates to a particular kind of router bit used with earth-moving equipment, e.g., tractor scrapers, bucket loaders, a dozer, and the like, for use in cutting into underlying terrain. More particularly, the present invention relates to an improved router bit having two parts, one of which may be permanently affixed to the earth-moving apparatus, while the other is separable from the former in order, inter alia, to reduce the ordinarily high cost of repair and replacement normally required when conventional unitary router bits become worn and ineffective.
2. The Prior Art
Most earth-moving apparatus includes a horizontally-elongated cutting edge for the purpose of cutting into the underlying terrain. This cutting edge is normally located in front of what is commonly called a scraper bowl, which is used to collect and hold the dirt sheared by the cutting edge. Secured to each side of the scraper bowl, adjacent and generally perpendicular to the cutting edge, are devices known as router bits. Router bits are used to slice vertically through the earth, perpendicular to the cutting edge, as the earth-moving equipment is being moved forwardly to ensure a clean cut and to protect the lower leading edges of the scraper bowl sides and the adjacent lateral ends of the cutting edge. If router bits are not provided, or if they are worn excessively, the lower leading edges, as well as the ends of the cutting edge, wear excessively, necessitating frequent time-consuming and expensive repair and, all too often, very costly replacement.
Conventional router bits are unitary in construction, normally manufactured by forging or casting, and are bulky because of the strength required for the bits. Normally, router bits are secured by bolts to the scraper side walls in order to perform their intended purpose, as aforesaid. Most conventional types of router bits will also include a metallic bar, or a thickened integrally formed rib which acts as a shield to protect the bolts from excessive wear due to the continuous passage of earth.
Conventional router bits, primarily because of their unitary construction, are often difficult to remove and expensive to repair and replace when they wear out. Replacement of router bits of a unitary structure involves taking the equipment out of service and loosening the bolts, known as plow bolts, and replacing the router bit. Since the router bits are of a unitary structure, a major portion of the bit is discarded. Normally four to five plow bolts hold each bit and the bolts are not readily accessible, are usually tightly installed requiring significant manual labor to loosen. Bolt threads may be damaged and bolt heads or nuts partially rounded, even though there may be bars or thickened edges which are intended to protect the bolt assembly. When such damage occurs to the bolt assembly because of the passage of dirt and rocks, replacement of the router bits may become a difficult chore.
Usually, the major portion of the upper section of a conventional router bit does not experience the degree of excessive wear that would require the need for constant repair and replacement of that particular part. Yet, because of its unitary construction, the entire router bit must be removed for repair and/or replacement even though only the lower portion is the only area affected and usually worn. In these situations, it is often necessary to replace, as well, the bolts used to secure the router bits to the scraper bowl sides. Naturally, this adds to the high cost of maintenance. Moreover, because router bits are usually formed of forgings, which are relatively expensive to fabricate and, thus, to replace, the constant expense and effort required to attend to their maintenance is rather high.
A typical prior art structure is that of U.S. Pat. No. 4,208,817 issued June 24, 1980 and the prior patents cited therein.